Monitoring of pesticides water pollution-The Egyptian River Nile

DDT contamination in water resources of some African countries and its impact on water quality and human health

Dichlorodiphenyltrichloroethane (DDT) usage has been prohibited in developed nations since 1972 but is exempted for use in indoor residual spraying (IRS) in developing countries, including African countries, for malaria control. There have been no previous reviews on DDT residues in water resources in Africa. The study aimed to provide a review of available research investigating the levels of DDT residues in water sources in Africa and to assess the consequent human health risks. A scoping review of published studies in Africa was conducted through a systematic electronic search using PubMed, Web of Science, EBSCO HOST, and Scopus. A total of 24 articles were eligible and reviewed. Concentrations of DDT ranged from non-detectable levels to 81.2 μg/L. In 35% of the studies, DDT concentrations surpassed the World Health Organization (WHO) drinking water guideline of 1 μg/L in the sampled water sources. The highest DDT concentrations were found in South Africa (81.2 μg/L) and Egypt (5.62 μg/L). DDT residues were detected throughout the year in African water systems, but levels were found to be higher during the wet season. Moreover, water from taps, rivers, reservoirs, estuaries, wells, and boreholes containing DDT residues was used as drinking water. Seven studies conducted health risk assessments, with two studies identifying cancer risk values surpassing permissible thresholds in water sampled from sources designated for potable use. Non-carcinogenic health risks in the studies fell below a hazard quotient of 1. Consequently, discernible evidence of risks to human health surfaced, given that the concentration of DDT residues surpassed either the WHO drinking water guidelines or the permissible limits for cancer risk in sampled drinking sources within African water systems. Therefore, alternative methods for malaria vector control should be investigated and applied.

Assessing Heavy Metals in the Sele River Estuary: An Overview of Pollution Indices in Southern Italy

Rapid industrialization, coupled with a historical lack of understanding in toxicology, has led in an increase in estuary pollution, frequently resulting in unexpected environmental situations. Therefore, the occurrence of heavy metals (HMs) constitutes a major environmental issue, posing a serious risk both to aquatic ecosystems and public health. This study aimed to evaluate the levels of eight HMs (As, Hg, Cd, Cr, Cu, Ni, Pb, and Zn) in water, suspended particles, and sediment near the Sele River estuary (Italy) in order to assess their environmental impacts on the sea and health risks for humans. The results revealed an increasing order of HM concentration according to the scheme suspended particulate matter (SPM) > sediment (SED) > dissolved phase (DP) and a moderate contamination status in sediment. The health risk assessment indicated that the non-carcinogenic risk was negligible. Carcinogenic risk, expressed as the incremental lifetime cancer risk (ILCR), was negligible for Cd and Ni and within tolerable limits for As, Pb, and Cr. The findings suggested that, even if there are currently no specific limits for chemical parameters in the transitional waters of Italy, monitoring systems should be implemented to determine pollution levels and implement effective steps to improve river water quality and reduce human health risks.

Effects of chlorpyrifos toxicity on brain, pseudobranchial neurosecretory system and swimming performance of a catfish, Heteropneustes fossilis

In the present study, it was aimed to evaluate the adverse effects of CPF on the histopathology of the optic tectum and cerebellum, pseudobranchial neurosecretory system (PNS), biochemical assays of brain tissue, and locomotory behavior in catfish, Heteropneustes fossilis. The fishes were exposed to an environmentally relevant concentration of 0.09 and 0.192 mg/L of CPF for 7, 15, and 30 d. The CPF toxicity induced degenerative changes with significantly decreased cell size, number, and nucleo-cytoplasmic (N/C) ratio of the PNS; and altered neuro-architectural pattern of optic tectum with degenerative changes in mononuclear and granular cells and necrotic variation in granular and Purkinje cells of the cerebellum. The Acetylcholinesterase (AChE) and Catalase (CAT) activity in the CPF-exposed brain was significantly decreased, whereas Superoxide dismutase (SOD) and Malondialdehyde (MDA) level was significantly increased in comparison with control. In CPF-exposed fishes, the respiratory movements and locomotory behavioral pattern like swimming speed, total distance traveled, time mobile, absolute turn angle, head: distance traveled, maximum speed were significantly decreased, whereas time immobile and time freezing episodes were significantly increased as compared to control fishes. The present study concludes that environmentally relevant concentration of CPF may induce histopathological, biochemical, physiological, and behavioral disturbances in a non-target organism, H. fossilis.

Mixed agricultural, industrial, and domestic drainage water discharge poses a massive strain on freshwater ecosystems: a case from the Nile River in Upper Egypt

Heavy metal and pesticide pollution of freshwater ecosystems, i.e., rivers, raises significant concerns worldwide, where practical solutions to reduce the threats become urgent need. Heavy metals and pesticides are top of the list of environmental toxicants endangering nature; therefore, pesticides and heavy metals were measured at 10 stations along the Al-Zennar agricultural drain and the Nile River at Assiut city in Upper Egypt, to assess potential negative impact on the water/sediment's quality. The sediment of the streambed is a sink for pesticides and heavy metals, where both water and sediments have higher contamination factor (CF) for Cd, Pb, Cr, Cu, and Zn. In addition, the Nile water is highly contaminated by PCBs. The distance to the point source and hydrodynamics (flow rate and stream gradient) has major influences in pollutant concentrations as indicated by regression models. Dilution effect and rapid sedimentation may comment on the lower concentrations of the pollutants in the Nile comparatively to the drain and on the water comparatively to the sediments. The physiochemistry of the stations has minor effect on the metal/pesticide concentration, where the variable importance of projection (VIP) of the partial least square model indicated that total dissolved solids (TDS), total suspended solids (TSS), SO42-, and BOD/TOC/COD are the main contributors to the metal/pesticide concentration. Concentrations were not correlated between water and sediment suggesting a historical accumulation in sediments and temporal variation in the pollution load in the Al-Zennar drain. Bray-Curtis clustering confirmed that heavy metals have the same anthropogenic source in contrast to natural source of both Mn and Fe.

Water quality, human health risk, and pesticides accumulation in African catfish and Nile tilapia from the Kitchener Drain-Egypt

Pesticides are toxic and could negatively impact humans and the ecosystem. The Kitchener Drain is among the longest drains in Egypt and carries a wide range of wastewater from the agriculture sector, which contains pesticides and may pollute the ecosystem. Thus, water quality, human health risk, and pesticide accumulation in African catfish and Nile tilapia from the Kitchener Drain-Egypt. The water and fish samples were collected from Kitchener Drain in Kafr Elsheikh Governorate, Egypt, during the four seasons. The results indicated that heptachlor and diazinon were undetected during the four seasons. However, endosulfan, chlorpyrifos, and dicofol were detected in winter and autumn. Only p,p'-DDT was detected during spring. Endosulfan, heptachlor, and aldrin were detected in Nile tilapia during winter. Only heptachlor and aldrin were detected during spring. Endosulfan, heptachlor, dicofol, p,p'-DDT, chlorpyrifos, and diazinon were detected in the autumn season. In summer, dicofol and p,p'-DDT were detected, while endosulfan, heptachlor p,p'-DDT, aldrin, chlorpyrifos, and diazinon were not detected. In African catfish, endosulfan, heptachlor, dicofol, and p,p'-DDT were detected during winter, while chlorpyrifos, aldrin, and chlorpyrifos, aldrin, and diazinon were not detected. In the spring season, endosulfan, heptachlor, and aldrin were detected. Endosulfan, heptachlor, dicofol, p,p'-DDT, aldrin, chlorpyrifos, and diazinon were detected in the autumn season. Similarly, in the summer season, endosulfan, heptachlor, dicofol, p,p'-DDT, aldrin, chlorpyrifos, and diazinon were detected. The sequence of estimated daily intake (EDI) in Nile tilapia during the four seasons is heptachlor > endosulfan > dicofol > p,p'-DDT > aldrin > diazinon > chlorpyrifos. The sequence of EDI in African catfish during the four seasons is endosulfan > p,p'-DDT > heptachlor > aldrin > dicofol > diazinon > chlorpyrifos. In conclusion, the results confirmed the absence of a hazard index for consuming Nile tilapia and African catfish collected from the Kitchener drain.

Nanobiopesticides: Are they the future of phytosanitary treatments in modern agriculture?

The world's population is continuously increasing; therefore, food availability will be one of the major concerns of our future. In addition to that, many practices and products used, such as pesticides and fertilizers have been shown harmful to the environment and human health and are assumed as being one of the main factors responsible for the loss of biodiversity. Also, climate change could agravate the problem since it causes unpredictable variation of local and regional climate conditions,which frequently favor the growth of diseases, pathogens and pest growth. The use of natural products, like essential oils, plant extracts, or substances of microbial-origin in combination with nanotechnology is one suitable way to outgrow this problem. The most often employed natural products in research studies to date include pyrethrum extract, neem oil, and various essential oils, which when enclosed shown increased resistance to environmental factors. They also demonstrated insecticidal, antibacterial, and fungicidal properties. However, in order to truly determine if these products, despite being natural, would be hazardous or not, testing in non-target organisms, which are rare, must start to become a common practice. Therefore, this review aims to present the existing literature concerning nanoformulations of biopesticides and a standard definition for nanobiopesticides, their synthesis methods and their possible ecotoxicological impacts, while discussing the regulatory aspects regarding their authorization and commercialization. As a result of this, you will find a critical analysis in this reading. The most obvious findings are that i) there are insufficient reliable ecotoxicological data for risk assessment purposes and to establish safety doses; and ii) the requirements for registration and authorization of these new products are not as straightforward as those for synthetic chemicals and take a lot of time, which is a major challenge/limitation in terms of the goals set by the Farm to Fork initiative.

Bioanalytical and chemical characterization of organic micropollutant mixtures in long-term exposed passive samplers from the Joint Danube Survey 4: Setting a baseline for water quality monitoring

Monitoring methodologies reflecting the long-term quality and contamination of surface waters are needed to obtain a representative picture of pollution and identify risk drivers. This study sets a baseline for characterizing chemical pollution in the Danube River using an innovative approach, combining continuous three-months use of passive sampling technology with comprehensive chemical (747 chemicals) and bioanalytical (seven in vitro bioassays) assessment during the Joint Danube Survey (JDS4). This is one of the world's largest investigative surface-water monitoring efforts in the longest river in the European Union, which water after riverbank filtration is broadly used for drinking water production. Two types of passive samplers, silicone rubber (SR) sheets for hydrophobic compounds and AttractSPETM HLB disks for hydrophilic compounds, were deployed at nine sites for approximately 100 days. The Danube River pollution was dominated by industrial compounds in SR samplers and by industrial compounds together with pharmaceuticals and personal care products in HLB samplers. Comparison of the Estimated Environmental Concentrations with Predicted No-Effect Concentrations revealed that at the studied sites, at least one (SR) and 4-7 (HLB) compound(s) exceeded the risk quotient of 1. We also detected AhR-mediated activity, oxidative stress response, peroxisome proliferator-activated receptor gamma-mediated activity, estrogenic, androgenic, and anti-androgenic activities using in vitro bioassays. A significant portion of the AhR-mediated and estrogenic activities could be explained by detected analytes at several sites, while for the other bioassays and other sites, much of the activity remained unexplained. The effect-based trigger values for estrogenic and anti-androgenic activities were exceeded at some sites. The identified drivers of mixture in vitro effects deserve further attention in ecotoxicological and environmental pollution research. This novel approach using long-term passive sampling provides a representative benchmark of pollution and effect potentials of chemical mixtures for future water quality monitoring of the Danube River and other large water bodies.

Self-reported assessment of compliance with pesticide rules

How pesticides are used is very important in determining the risk they pose to both the user, and the environment. Given they can have toxic properties, if pesticides are misused they could cause serious harm to the users health as well as a range of environmental damage. Despite this, very little research has quantified whether agricultural use of pesticides is compliant with the legally binding obligations and associated guidance surrounding application. In this survey we used an online, fully anonymous, questionnaire to ask Irish farmers about how they use pesticides. We used a self-reporting methodology, directly asking farmers about their compliance levels. We had a total of 76 unique valid respondents. Our respondents covered the broad range of Irish agriculture, and we quantified how this relates to national demographics. Overall compliance regarding pesticide use was high, with the majority of respondents complying the majority of the time. However, we also found a sizable group who report low compliance levels for certain topics. Respondents reported the highest levels of non-compliance with the use of personal protective equipment, with nearly half of all respondents admitting to not wearing certain required protective equipment on a regular basis. In contrast, for some areas like application rate, very high compliance was reported. Moderate levels of non-compliance with bee protective mitigation measures were found, and some reported practices like not emptying or washing out the spray tank between sprays could have serious impacts on pollinators, soil organisms and other non-targets. Additionally, a minority of respondents admitted to actions which could cause serious water course pollution. As the first survey on a range of pesticide compliance topics within a developed nation, the compliance seen is very high compared to levels in developing nations. Our results demonstrate that the assumption that all legal obligations and guidance surrounding pesticide use are followed is unfounded, but that the majority of the respondents are mostly compliant. Education or enforcement should be targeted to certain areas where compliance is weakest to minimise harm from pesticide use. Reducing the non-compliance we report here could benefit both farmer and environmental health, and ensure that pesticides are used in a manner that risk assessment has deemed safe.

Meiosis-mediated reproductive toxicity by fenitrothion in Caenorhabditis elegans from metabolomic perspective

Fenitrothion (FNT), an organophosphorus insecticide, is widely detected in the living environment. The reproductive and endocrine toxicity of FNT to biological communities has been ever reported, but potential mechanism and reproductive toxicity dose effect remain unclear. In our study, we constructed Caenorhabditis elegans model to analyze the reproductive toxicity mechanism of FNT based on metabolomics and evaluated its reproductive toxicity dose effect using benchmark dose (BMD)method. Our results showed that FNT exposure significantly reduced brood size, number of germ cells, and delayed gonadal development in nematodes. Non-targeted metabolomics revealed that FNT exposure caused significant metabolic disturbances in nematodes, leading to a significant reduction in the synthesis of cortisol and melatonin, and the latter played a mediating role in the effects of FNT on number of germ cells. We further found that the levels of these two hormones were significantly negative correlated with the expression of the androgen receptor nhr-69 and affected the meiosis of germ cells by regulating the nhr-69/ fbf-1/2 /gld-3 /fog-1/3 pathway. Meanwhile, the study found the BMDL10s for N2 and him-5 mutant were 0.411 μg/L by number of germ cells and 0.396 μg/L by number of germ cells in the meiotic zone, respectively, providing a more protective reference dose for ecological risk assessment of FNT. This study suggested that FNT can affect androgen receptor expression by inhibiting cortisol and melatonin secretion, which further mediate the meiotic pathway to affect sperm formation and exert reproductive toxicity, and provides a basis for setting reproductive toxicity limits for FNT.

Developmental toxicity of chlorpyrifos-methyl and its primary metabolite, 3,5,6-trichloro-2-pyridinol to early life stages of zebrafish (Danio rerio)

Chlorpyrifos-methyl (CPM) is one of the thiophosphate insecticides, and it is mainly metabolized to 3,5,6-trichloro-2-pyridinol (TCP) in the environment. As CPM is a strongly toxic and TCP is persistent in the environment, CPM and TCP need to be evaluate their toxicities using animal model organisms. With this regard, CPM and TCP were treated on zebrafish (Danio rerio) embryos and LC₅₀ values were determined as over 2000 μg/L and 612.5 μg/L, respectively. For the hatchability, CPM did not exhibit any interference, while TCP showed weak inhibition. In the CPM-treated embryos, pericardial edema and bleeding were observed at 48 hpf, but recovered afterwards. The pericardial edema and yolk sac edema were observed in TCP-treated zebrafish embryos at the concentration of 500 μg/L after 72 hpf. TCP induced abnormal heart development and the heartbeat was dramatically decreased in Tg(cmlc2:EGFP) embryos at the level of 500 μg/L. The expression level of heart development-related genes such as gata, myl7, and cacna1c was significantly decreased in the TCP 500 μg/L-treated embryos at the 96 hpf. Taken together, TCP appears to be more toxic than the parent compound towards the zebrafish embryos. It is highly requested that TCP needs to be monitored with a strong public concern because it affects presumably heart development in early-stage aquatic vertebrates.

Molecular Dietary Analysis of Three Sympatric Mustelidae in Northeast China

Diet analysis is essential to fully understand the biology of a species and its function within the ecosystem, as well as being key in identifying food web interactions and the population dynamics of predators and prey. The understanding of the diet of small to mid-sized carnivores remains generally lacking or uninformative due to the inability for taxonomic resolution based on morphology. The yellow-throated marten (Martes flavigula), Eurasian river otter (Lutra lutra), and Siberian weasel (Mustela sibirica) are three important Mustelidae species in ecosystems of northeast China. Based on fecal DNA and a next-generation sequencing (NGS) approach, we analyzed the vertebrate prey of these three sympatric Mustelidae. Prey included 7 mammalian taxa, 10 fishes, 2 birds, and 2 amphibians, with 85% of the taxa assigned to the species level. In total, twenty-one vertebrate prey taxa were identified from seven yellow-throated martens, eight Eurasian river otters, and two Siberian weasels. Concerning identified dietary species, 10 taxa were consumed by yellow-throated martens, 14 by Eurasian river otters, and 4 by Siberian weasels. Some prey species were identified in more than one species. Amphibians and fishes were the most dominant Eurasian river otter prey categories, whereas Eurasian badger (Meles leucurus), birds, and rodents were the main yellow-throated marten prey; amphibians and rodents were largely contained in Siberian weasel prey. Among prey items, Dybowski's frog (Rana dybowskii) and Korean field mouse (Apodemus peninsulae) were identified in all three Mustelidae species but our analyses suggest potential diet preferences among Mustelidae species. Future studies should focus on understanding the trophic relationships of these three Mustelidae species, providing valuable information for their conservation planning.

The toxic effects of combined exposure of chlorpyrifos and p, p'-DDE to zebrafish (Danio rerio) and tissue bioaccumulation

Pesticides are widely used and frequently detected in the environment. The evaluation on the toxic effects of the co-exposure of two or more pesticides or related metabolites could reflect the real situation of the exposing risks. In this study, zebrafish was used as a model to investigate the potential toxic interactions of chlorpyrifos and 1,1-dichloro-2,2-bis(p-chlorophenyl)ethylene (p,p'-DDE) on the survival rate, oxidative stress response and neurotoxicity, as well as their bioaccumulation and distribution in tissues. Co-exposure of chlorpyrifos and p,p'-DDE resulted in significant additive acute toxic effects on adult zebrafish with model deviation ratio (MDR) = 1.64. Both 7-day short-term at 1% LC₅₀ and 35-day long-term at 0.5% LC₅₀ co-exposure of chlorpyrifos with p,p'-DDE (50 and 100 µg/L) significantly reduced the survival rate of zebrafish colony to 75 and 82.5%. Co-exposure of chlorpyrifos and p,p'-DDE contributed to increased activity of antioxidant enzyme CAT, SOD and GST and excessive MDA generation, and decreased activity of CarE, CYP450 and AChE, compared with either single exposure of them. In co-exposure, the bioaccumulation of chlorpyrifos and p,p'-DDE was significantly different from the single exposure group. Overall, this study unraveled the potential toxic interaction of chlorpyrifos and p,p'-DDE on zebrafish and provided reference for environmental risk assessment of pesticide mixture.

Occurrence, human health, and ecotoxicological risk assessment of pesticides in surface waters of the River Nile's Rosetta Branch, Egypt

In Egypt, the shortage of freshwater resources and their pollution constitutes a growing concern. Therefore, the objectives of this study were to (i) monitor the occurrence and spatiotemporal variations of 100 pesticides in surface water samples collected monthly (from July 2018 to June 2019) from El-Rahawy, Sabal, and Tala sampling sites along the Rosetta branch of the River Nile in Egypt, (ii) identify potential non-carcinogenic health risks for the local people through the lifetime consumption of contaminated drinking water, and (iii) perform an ecological risk assessment of aquatic organisms upon exposure to pesticides detected in surface waters based on the risk quotients (RQs) method. Of the 100 pesticides analyzed, 22 belonging to 11 chemical families were detected, and 75.5% of surface water samples were contaminated with one or more pesticide residues. The most frequently detected pesticide was malathion (57%), followed by chlorpyrifos (54%), atrazine (23%), and carbendazim (20%). Spatial distribution showed that the El-Rahawy site had the highest pesticide load (38.47 μg/L), and Sabal had the lowest (16.29 μg/L). Temporal variations revealed that the highest total pesticide concentrations were detected in summer (27.98 μg/L) compared to spring (23.16 μg/L), winter (19.18 μg/L), and autumn (11.85 μg/L). For non-carcinogenic risks of pesticides detected in surface water, the target hazard quotient (THQ) values were less than one. This implies that there is no potential human risk from exposure to drinking water at the sites under study. However, 13 pesticides presented high-risk quotients (RQ > 1), posing potential ecological risks to aquatic organisms.

Chlorpyrifos removal: Nb/boron-doped diamond anode coupled with solid polymer electrolyte and ultrasound irradiation

Chlorpyrifos is an organophosphorus insecticide, acaricide and miticide used worldwide for the control of soil-borne insect pests. It must be considered as a substance of growing concern, given its use, toxicity, environmental occurrence, and potential for regional to long-range atmospheric transport. Considering the incomplete removal attained by conventional water treatment processes, we investigated the efficiency of electrolytic radicals production and sonoelectrolysis on the degradation of the pesticide. The treatment has been conducted in a novel electrochemical reactor, equipped with a boron-doped diamond anode and a solid polymer electrolyte (SPE). Different current intensity and times have been tested and coupled with sonication at 40 kHz. Up to 69% of chlorpyrifos was completely removed in 10 min by electrolysis operated at 0.1 mA, while 12.5% and 5.4% was converted into the treatment intermediates 3,5,6-trichloro-2-pyridinol (TCP) and diethyl (3,5,6-trichloropyridin-2-yl) phosphate, respectively. Ultrasound irradiation did not enhance the removal efficiency, likely due to mass transport limitations, while the energy consumption increased from 8.68∙10- 6 to 9.34∙10- 4 kWh µg- 1 removed. Further research is encouraged, given the promising processing by the SPE technology of low conductivity solutions, as pharmaceuticals streams, as well as the potential for water and in-situ groundwater remediation from different emerging pollutants as phytosanitary and personal care products.

Distribution and ECo-Toxicological Risk Assessment of Legacy Persistent Organic Pollutants in Surface Water of Talar, Babolrood and Haraz Rivers

In the outer Alborz Range in the Northern Province of Iran, the Haraz, Talar and Babolrood Rivers are the three largest rivers where most of the agricultural, aquacultural and industrial activities are found. Total indicator polychlorinated biphenyls (iPCBs) ranged ND–474, ND–273 and ND–559 ng/L in Haraz, Talar and Babolrood Rivers, respectively. Significantly lower (p < 0.05) concentrations of DDT, lindane and dieldrin were observed in the upstream stations than downstream stations of both Babolrood and Haraz Rivers. However, in Talar River, PCB residues in upstream was significantly higher (p < 0.05) than downstream. Furthermore, PCB-28 in Talar River and PCB-101 and PCB-153 in Bablrood and Haraz Rivers were high in water samples at all stations. A significant difference was observed among the stations. In October, November and December, there was negligible variations in total PCB concentration among the stations. Alarming levels of some of the legacy persistent organic pollutants (POPs) may pose adverse effects on the aquatic species dwelling in the Talar, Babolrood and Haraz Rivers of Iran.

Risk assessment of the chiral pesticide fenamiphos in a human model: Cytochrome P450 phenotyping and inhibition studies

Fenamiphos (FS) is a chiral organophosphate pesticide that is used to control nematodes in several crops. Enantioselective differences may be observed in FS activity, bioaccumulation, metabolism, and toxicity. Humans may be exposed to FS through occupational and chronic (food, water, and environmental) exposure. FS may cause undesirable CYP450 pesticide-drug interactions, which may impact human health. Here, the CYP450 isoforms involved in enantioselective FS metabolism were identified, and CYP450 inhibition by rac-FS, (+)-FS, and (-)-FS was evaluated to obtain reliable information on enantioselective FS risk assessment in humans. CYP3A4 and CYP2E1 metabolized FS enantiomers, and CYP2B6 may participate in rac-FS metabolism. In addition, rac-FS, (+)-FS, and (-)-FS were reversible competitive CYP1A2, CYP2C19, and CYP3A4/5 inhibitors. High stereoselective inhibition potential was verified; rac-FS and (-)-FS strongly inhibited and (+)-FS moderately inhibited CYP1A2. Stereoselective differences were also detected for CYP2C19 and CYP3A4/5, which were strongly inhibited by rac-FS, (+)-FS, and (-)-FS. Our results indicated a high potential for CYP450 drug-pesticide interactions, which may affect human health. The lack of stereoselective research on the effect of chiral pesticides on the activity of CYP450 isoforms highlights the importance of assessing the risks of such pesticides in humans.

Quantitative evaluation and the toxicity mechanism of synergism within three organophosphorus pesticide mixtures to Chlorella pyrenoidosa

Organophosphorus pesticide (OPP) pollutants in the environment pose toxicity risks to living organisms, and the possible toxicity mechanism needs to be further clarified. Therefore, the individual and combined toxicity of three OPPs namely acephate (ACE), trichlorfon (TRI) and glyphosate (GIY) towards a freshwater green alga Chlorella pyrenoidosa (C. pyrenoidosa) was investigated by the time-dependent microplate toxicity analysis method. Here, a ternary mixture system of the three OPPs including five rays with different concentration ratios was designed by the uniform design ray method. The standard additive reference model, concentration addition (CA), was used to analyse toxicity interaction within ternary mixtures and the toxicity interaction intensity was characterized using a deviation from CA model (dCA). Besides, the effects of the three OPPs and their mixtures on the chlorophyll (CHL) content, superoxide dismutase (SOD) activity and malondialdehyde (MDA) content of C. pyrenoidosa were also investigated to explore the possible mechanisms. The results show that toxicity of the three pesticides and their ternary mixture rays is time-dependent and the combined toxicity correlates well with the components, ACE and GLY. It is likely that there is a significant time-dependent synergism in ternary mixtures induced by ACE and GLY. The synergism intensity of the ternary mixtures is not more than 30% at the whole experimental concentration level. The CHL reduction rate and MDA content of C. pyrenoidosa increase, while the SOD activity of C. pyrenoidosa decreases with the lengthening of exposure time under the action of the three pesticides and their ternary mixtures. So, the possible mechanism of the three pesticides and their mixtures may be by affecting the photosynthesis, and then causing oxidative damage to C. pyrenoidosa cells. The results can provide reference for the combined toxicity assessment of OPPs to living organisms.

Ecotoxicity of chlorpyrifos to aquatic organisms: A review

Pesticides play an important role in promoting agricultural development, while their unreasonable use has led to environmental problems. Chlorpyrifos (CPF), a typical organophosphate pesticide, is used globally as an insecticide in agriculture. The extensive application of CPF has resulted in water contamination, and CPF has been detected in rivers, lakes, seawater, and even in rain. In the present review, CPF was selected due to its extensive use in agriculture and higher detection rate in surface waters. In this review we summarised the evidence related to CPF pollution and focused on discussing the ecotoxicity of CPF to aquatic systems and revealed the mechanism of action of CPF. The aim of this literature review was to summarise the knowledge of the toxicity to marine and freshwater organisms of CPF as well as try to select a series of sensitive biomarkers, which are suitable for ecotoxicological assessment and environmental monitoring in aquatic systems.

Purification and characterization of a novel fenamiphos hydrolysing enzyme from Microbacterium esteraromaticum MM1

Fenamiphos is a neurotoxic organophosphorus pesticide used widely to control pests of crops. Fenamiphos and its toxic oxidation products have been detected in surface and groundwaters. A novel enzyme capable of hydrolysing P-O-C bond of fenamiphos is purified from Microbacterium esteraromaticum MM1 total cellular protein using a combination of methods. The purified fenamiphos hydrolysing enzyme (FHE) was identified as enolase (phosphopyruvate hydratase), a housekeeping enzyme with molecular mass and pI value of 45 kDa and 4.5, respectively. The optimum pH and temperature for the activity of the FHE are 7 and 25 °C, respectively. We studied the influence of metal ions and inhibitors on the enzyme activity. The enzyme was strongly activated by Mg²⁺ whereas Hg²⁺ and phenylmethyl sulfonyl fluoride (PMSF) inhibited the enzyme. The kinetic parameters, K_m and V_max for fenamiphos hydrolysis were estimated to be 584.15 ± 16.22 μM and 6.46 ± 0.13 μM min^-1, respectively. The FHE was functionally active against its original substrate (2-phosphoglycerate) with K_m value of 5.82 ± 1.42 μM and V_max of 4.2 ± 0.1 μM min^-1. This enzyme has great potential for its application in the detoxification of fenamiphos and its warfare homologs. To our knowledge, this is the first report on the purification of fenamiphos hydrolysing enzyme.

Hydrolysis of Amisulbrom in Buffer Solutions and Natural Water Samples: Kinetics and Products Identification

In this study, the hydrolysis of amisulbrom in buffer solutions and natural water samples were investigated. Effects of pH and temperature were tested in buffer solutions. Amisulbrom was stable in acidic and neutral aqueous solutions at 25°C, while quickly hydrolyzed with a half-life of 4.5 days (25°C) at pH 9.0. The kinetics rate equation was determined as k = 1.0234 × 10¹⁰ exp (-61.3760/R·T) (R² = 0.9642) for hydrolysis of amisulbrom at pH 9.0. The pH, ionic strength, and solubility were important factors influencing the hydrolysis of amisulbrom in natural water samples. Furthermore, three hydrolysis products were separated and identified in buffer solution (pH 9.0) and natural water samples. A tentative transformation mechanism of amisulbrom was proposed to rationalize the formation of HPs (hydrolysis products) based on their structural identification, DFT (density functional theory), and hydrolysis profiles. Toxicity prediction using the quantitative structure-activity relationship model revealed that the HP-I, and HP-II were more toxic than the parent amisulbrom. This investigation was the first to evaluate the behavior of amisulbrom hydrolysis in aquatic systems.

Combination of vortex assisted binary solvent microextraction and QuEChERS for the determination of prothiofos, oxadiargyl, and gamma-cyhalothrin in water and pineapple samples by gas chromatography mass spectrometry

An accurate and sensitive dispersive liquid-liquid microextraction method based on binary solvents was used to enrich prothiofos, oxadiargyl, and gamma-cyhalothrin for quantification by GC-MS. The combination of two extraction solvents (binary mixture) resulted in higher extraction efficiencies compared to the single solvent extraction systems. Parameters of the binary extraction method where optimized to enhance the extraction output of the analytes. The limits of detection calculated for the analytes ranged between 0.59 and 1.6 ng/mL. Linear calibration plots of the analytes covered wide concentration ranges with R² values greater than 0.9996 and percent relative standard deviation lower than 10%. Spiked recovery experiments were performed well and wastewater at two different concentrations and satisfactory results (89-104%) were obtained. The binary solvent microextraction method was combined with QuEChERS to quantify the analytes in pineapple matrix, using matrix matching method to enhance the accuracy of the method to almost 100%.

Rural Households’ Willingness to Accept Compensation Standards for Controlling Agricultural Non-Point Source Pollution: A Case Study of the Qinba Water Source Area in Northwest China

Agricultural non-point source pollution (ANSP) has become one of the main sources of pollution in water source areas. An effective solution to this problem is the use of ecological compensation to encourage rural households to adopt agricultural pollution control measures. This study aims to answer two questions: How much compensation should be given to encourage rural households in water source areas to participate in ANSP control? What factors will influence their participation? In this study, paddy rice planting in water source area has been used as an example aiming to answer these questions. This study used the random parameter logit (RPL) model with survey data from 632 rural households in the Qinba water source area to empirically analyze rural households’ willingness to accept compensation for ANSP control and the influencing factors of this willingness. From this information, the compensation standards for ANSP control in a water source area were calculated. The results show that (1) compensation had a significant incentive effect on rural households’ willingness to control ANSP. The marginal compensation standard for reducing the use of fertilizer and pesticide was $3.40/ha and $2.00/ha, respectively. The compensation standard for not applying chemical fertilizer and pesticide at all was $540.23/ha. (2) There was heterogeneity in rural households’ preference for ANSP control compensation policies. Rural households characterized by younger residents, higher family income, higher perception of the ecological benefits, and higher perception of government policy were more willing to participate in the compensation policy. It is suggested that rural households showed a strong preference for ANSP control policies by considering both of their economic losses and ecological benefits. Our study contributes to the literature by enriching the evaluation method in providing references for the compensation of ANSP control policies

Distribution and risk assessment of banned and other current-use pesticides in surface and groundwaters consumed in an agricultural catchment dominated by cocoa crops in the Ankobra Basin, Ghana

The existence of pesticides, such as organochlorine pesticides, parathion-ethyl, methamidophos which is banned globally and some current-use non-banned pesticides of organophosphorus and synthetic pyrethroids in freshwater sources is an ecological and public health concern in many countries, including Ghana. Prompted by this concern, the exposure levels and risk assessment of these pesticides to humans and non-target organisms via groundwater and surface water sources in an agricultural catchment dominated by cocoa crops in the Ankobra Basin, Ghana, were investigated. The individual concentrations of the banned pesticides in the surface water and groundwater samples varied from < LOD to 0.110 μg/L and < LOD to 0.055 μg/L, respectively, while the concentrations of the non-banned pesticides ranged from < LOD to 0.925 μg/L and < LOD to 2 μg/L, respectively. The mean concentrations of chlorpyrifos, cypermethrin, p,p'-DDT and pirimiphos-methyl in some water sources exceeded the EU limit of 0.1 μg/L. Some surface water sources were more contaminated with DDTs, endrin, dieldrin, methoxychlor, chlorpyrifos, and HCH isomers than were freshwater sources in river basins in some countries of the world. Chlorpyrifos, p,p'-DDT and methoxychlor were ubiquitous in both water sources. The hydrochemical and compositional profiles of the pesticides indicate that water-exchange and secondary porosities in the bedrock likely contributed to the occurrence of the pesticides in the water sources. The pesticides were of low risk to humans that consume the water, but considering the US EPA safe limit for carcinogenic effects of 10^-6, the high levels of DDTs, β-HCH, and dieldrin in some of the surface water and groundwater sources may cause cancer in children or infants. The toxicity of pesticide mixtures to surface water non-target organisms decreased in the order of fish > Daphnia magna > algae. The pesticides in the water sources were anthropogenic in origin and recently used. DDT and HCH in the water were of technical-grade origin.

Distribution pattern of persistent organic pollutants in aquatic ecosystem at the Rosetta Nile branch estuary into the Mediterranean Sea, North of Delta, Egypt

The objective of this study was to evaluate the distribution pattern of persistent organic pollutants in water, sediment and aquatic biota represented by Oreochromis niloticus and Donax trunculus at the Rosetta Nile branch estuary. α-HCH, p,p'-DDE and polychlorinated biphenyls were the predominant compounds detected at ranges of 0.54-4.90 ng/l water, 0.75-2.41 ng/g, d. wt. sediment and 2.19-28.11 ng/g, fresh wt. biota. β and γ-HCHs, endosulfan compounds, heptachlor and heptachlor epoxide were at low detection frequencies. Totally, the organochlorine pollutants were at high levels and abundances in Donax spp. than in Tilapia spp. followed by sediment and water. These levels were ranged between lower and higher than those found by the other studies established in Egypt, and well below its tolerable residue levels in fish. A correlation was found for the quantified pollutants between water, sediment and biota. This is clearly reflecting the bioaccumulation properties of these compounds.